Electrode assembly for secondary battery

ABSTRACT

An electrode assembly, including an electrode plate at opposite sides of a separator, the electrode plate including a double-sided coated region having an active material on opposite sides of a substrate forming a current collector, and a single-sided coated region having an active material on a single surface of the substrate, wherein the single-sided coated region has a resistance that is higher than a resistance of the double-sided coated region.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application based on pending application Ser. No.16/465,869, filed May 31, 2019, the entire contents of which is herebyincorporated by reference.

Application Ser. No. 16/465,869 is the U.S. national phase applicationbased on PCT Application No. PCT/KR2017/014374, filed Dec. 8, 2017,which is based on Korean Patent Application No. 10-2016-0167783, filedDec. 9, 2016, the entire contents both being hereby incorporated byreference.

TECHNICAL FIELD

The present disclosure relates to a rechargeable battery including anelectrode plate having a double-sided coated region and a single-sidedcoated region.

BACKGROUND ART

With advancement of technology for mobile devices, demand forrechargeable batteries as energy sources has been increasing. Arechargeable battery can be repeatedly charged and discharged, unlike aprimary battery.

A low-capacity rechargeable battery is used for small portableelectronic devices such as a mobile phone, a notebook computer, and acamcorder, and a large-capacity rechargeable battery is used as a powersupply for driving a motor such as for a hybrid car.

For example, the rechargeable battery includes an electrode assembly forcharging and discharging and is formed by spirally winding a negativeelectrode plate, a separator, and a positive electrode plate, a pouchfor accommodating the electrode assembly therein, and an electrode tabfor drawing out the electrode assembly to the outside of the pouch.

For example, the negative electrode plate includes a double-sided coatedregion formed by coating an active material on opposite surfaces of asubstrate, and a single-sided coated region formed by coating an activematerial on a single surface of the substrate. The negative electrodeplate is formed by using a same loading level of the active materialwithout considering the double-sided coated region and the single-sidedcoated region or by coating the active material in a same manner withoutconsidering whether carbon is coated on the substrate.

Therefore, resistance is reduced in the single-sided coated region ascompared with the double-sided coated region, and thus a current amountdifference occurs between the double-sided coated region and thesingle-sided coated region. A difference in the amount of charge anddischarge in the negative electrode plate causes non-uniformdeterioration of the negative electrode plate. This deteriorates thecycle-life of the rechargeable battery.

DISCLOSURE Technical Problem

An exemplary embodiment of the present invention has been made in aneffort to provide a rechargeable battery that minimizes a current amountdifference between a double-sided coated region and a single-sidedcoated region by increasing resistance of the single-sided coated regionto be higher than that of the double-sided coated region in an electrodeplate (e.g., a negative electrode plate).

Technical Solution

An exemplary embodiment of the present invention has been made in aneffort to provide a rechargeable battery in which a loading level of anactive material in a single-sided coated region is higher than that of adouble-sided coated region.

An exemplary embodiment of the present invention has been made in aneffort to provide a rechargeable battery that improves relatively lowadherence of a single-sided coated region by including a binder layerformed by pattern-coating a binder along the single-sided coated regionin an electrode plate.

An exemplary embodiment of the present invention has been made in aneffort to provide a rechargeable battery in which a single-sided coatedregion is formed by pattern-coating an active material on a singlesurface of a substrate to prevent the single-sided coated region fromincluding a carbon-coating layer in an electrode plate including thecarbon-coating layer.

An exemplary embodiment of the present invention has been made in aneffort to provide a rechargeable battery in which orientations of adouble-sided coated region and a single-sided coated region aredifferent in an oriented electrode plate.

An exemplary embodiment of the present invention has been made in aneffort to provide a rechargeable battery in which a double-sided coatedregion is formed of an oriented layer while a single-sided coated regionis formed of a non-oriented layer, or a double-sided coated region isformed of a high oriented layer while a single-sided coated region isformed of a low oriented layer.

An exemplary embodiment of the present invention provides a rechargeablebattery including: an electrode assembly formed by disposing anelectrode plate at opposite sides of a separator and spirally windingthe separator and the electrode plates; and a pouch configured toaccommodate the electrode assembly therein and to draw out an electrodetab connected to the electrode plates to the outside thereof, whereinthe electrode plate includes: a double-sided coated region formed bycoating an active material on opposite sides of a substrate forming acurrent collector; and a single-sided coated region formed by coating anactive material on a single surface of the substrate, and whereinresistance of the single-sided coated region is higher than that of thedouble-sided coated region.

The single-sided coated region may be disposed at at least one of awinding center of the electrode assembly 10 and an outermost woundposition thereof.

The electrode plate may include: a negative electrode plate disposed ona first surface of the separator to form a negative electrode; and apositive electrode plate disposed on a second surface of the separatorto form a positive electrode, and the single-sided coated region may beformed in the negative electrode plate.

A substrate of the positive electrode plate may be further spiral-woundinside the single-sided coated region of the negative electrode plate atthe winding center.

The substrate of the positive electrode plate may be further spirallywound on the outermost wound position of the single-sided coated regionof the negative electrode plate.

The double-sided coated region may be formed on opposite surfaces of thesubstrate to have a first thickness t1, and the single-sided coatedregion may be formed on a single surface of the substrate to have asecond thickness t2 that is larger than the first thickness.

The double-sided coated region may be formed by coating an activematerial on opposite surfaces of the substrate, while the single-sidedcoated region may further include a binder layer formed by coating abinder on a single surface of the substrate, and may be formed bycoating an active material on the binder layer.

The double-sided coated region may further include a carbon-coatinglayer on opposite surfaces of the substrate, and may be formed bycoating an active material on the carbon-coating layer, while thesingle-sided coated region may be formed by coating an active materialon a single surface of the substrate.

The double-sided coated region may be formed of an oriented layer bycoating an active material on opposite surfaces of the substrate, andthe single-sided coated region may be formed of a non-oriented layer bycoating an active material on a single surface of the substrate.

The double-sided coated region may be formed of a high oriented layer bycoating an active material on opposite surfaces of the substrate, andthe single-sided coated region may be formed of a low oriented layerthat is oriented less than the high oriented layer by coating an activematerial on a single surface of the substrate.

Advantageous Effects

As such, according to the exemplary embodiments of the presentinvention, it is possible to minimize the current amount differencebetween the double-sided coated region and the single-sided coatedregion by increasing resistance of the single-sided coated region to behigher than that of the double-sided coated region in the electrodeplate. This may cause uniform deterioration of the electrode plate,thereby improving the cycle-life of the rechargeable battery.

DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exploded perspective view of a rechargeablebattery according to a first exemplary embodiment of the presentinvention.

FIG. 2 illustrates a perspective view of the electrode assembly of FIG.1 , which is assembled.

FIG. 3 illustrates a cross-sectional view of an electrode assembly,which is applied to the rechargeable battery of FIG. 1 .

FIG. 4 illustrates a partial cross-sectional view of a negativeelectrode plate, which is applied to the electrode assembly of FIG. 3 .

FIG. 5 illustrates a partial cross-sectional view of a negativeelectrode plate, which is applied to an electrode assembly of arechargeable battery according to a second exemplary embodiment of thepresent invention.

FIG. 6 illustrates a partial cross-sectional view of a negativeelectrode plate, which is applied to an electrode assembly of arechargeable battery according to a third exemplary embodiment of thepresent invention.

FIG. 7 illustrates a partial cross-sectional view of a negativeelectrode plate, which is applied to an electrode assembly of arechargeable battery according to a fourth exemplary embodiment of thepresent invention.

FIG. 8 illustrates a partial cross-sectional view of a negativeelectrode plate, which is applied to an electrode assembly of arechargeable battery according to a fifth exemplary embodiment of thepresent invention.

FIG. 9 illustrates a graph comparing thicknesses, capacities, andcycle-lives of single-sided coated regions of rechargeable batteriesaccording to a conventional art (the single-sided coated region anddouble-sided coated region having a same thickness, the single-sidedcoated region including a carbon-coating layer) and the first and thirdexemplary embodiments of the present invention (the thickness ofsingle-sided coated region being larger than that of the double-sidedcoated region, the single-sided coated region including nocarbon-coating layer).

FIG. 10 illustrating a graph comparing capacities and cycle-lives ofrechargeable batteries according to a conventional art (no binder layerbeing applied to single-sided coated region) and the second exemplaryembodiment of the present invention (binder layer being applied tosingle-sided coated region).

FIG. 11 illustrates a cross-sectional view of an electrode assembly,which is applied to the rechargeable battery of FIG. 1 according to amodified exemplary embodiment.

MODE FOR INVENTION

Hereinafter, the present invention will be described more fully withreference to the accompanying drawings, in which exemplary embodimentsof the invention are shown. As those skilled in the art would realize,the described embodiments may be modified in various different ways, allwithout departing from the spirit or scope of the present invention. Thedrawings and description are to be regarded as illustrative in natureand not restrictive. Like reference numerals designate like elementsthroughout the specification.

FIG. 1 illustrates an exploded perspective view of a rechargeablebattery according to a first exemplary embodiment of the presentinvention, and FIG. 2 illustrates a perspective view of the electrodeassembly of FIG. 1 , which is assembled. Referring to FIG. 1 and FIG. 2, according to the first exemplary embodiment, the rechargeable batteryincludes an electrode assembly 10 for charging and discharging acurrent, and a pouch 20 for accommodating the electrode assembly 10 andan electrolyte.

FIG. 3 illustrates a cross-sectional view of an electrode assembly,which is applied to the rechargeable battery of FIG. 1 . Referring toFIG. 1 to FIG. 3 , the electrode assembly 10 is formed by disposing afirst electrode plate (referred to as a “positive electrode plate” forconvenience) 11 and a second electrode plate (referred to as a “negativeelectrode plate” for convenience) 12 with a separator 13 therebetween,and spirally winding the positive electrode plate 11, the separator 13,and the negative electrode plate 12.

The electrode assembly 10 is formed flat by pressing side surfaces of aspirally wound cylindrical shape. The electrode assembly 10 may be drawnout to the outside of the pouch 20 through electrode tabs 14 and 15 thatare respectively connected to the positive electrode plate 11 and thenegative electrode plate 12 to be provided at one side or opposite sides(not illustrated) of a spiral-wound cross-section thereof.

The positive electrode plate 11 includes a coated region 32 formed bycoating a positive active material on a substrate 31 that constitutes acurrent collector as a metal thin plate, and an uncoated region 33exposed without applying the positive active material on the substrate31. For example, the substrate 31 of the positive electrode plate 11 andthe electrode tab 14 connected to the uncoated region 33 may be formedof a same material, e.g., aluminum (Al).

The negative electrode plate 12 includes a coated region 36 formed bycoating a negative active material that is different from the activematerial of the positive electrode plate 11 on a substrate 35 thatconstitutes a current collector as a metal thin plate, and an uncoatedregion 37 that is exposed without applying the negative active materialon the substrate 35. For example, the substrate 35 of the negativeelectrode plate 12 and the electrode tab 15 connected to the uncoatedregion 37 may be formed of a same material, e.g., nickel (Ni).

Referring again to FIG. 1 and FIG. 2 , in the pouch 20, a sealingportion 23 is formed by thermally fusing outer circumferences of a firstcasing member 21 and a second casing member 22, which are separated orintegrally connected (not illustrated). The electrode tabs 14 and 15electrically connect the inside and the outside of the pouch 20 throughthe sealing portion 23. Insulation members 16 and 17 electricallyinsulate the electrode tabs 14 and 15 to electrically isolate theelectrode tabs 14 and 15 and the pouch 20.

The pouch 20 may be formed to have a multi-layered sheet structure thatsurrounds the outside of the electrode assembly 10. For example, thepouch 20 includes a polymer sheet 121 that forms an inner surface toperform electrical insulation and thermal fusion, a nylon sheet 122 forforming an outer surface to perform protection, and a metal sheet 123.

The nylon sheet 122 may be replaced with a PET (polyethyleneterephthalate) sheet or a PET-nylon composite sheet. The metal sheet 123is interposed between the polymer sheet 121 and the nylon sheet 122, andmay be formed of an aluminum sheet.

The pouch 20 accommodates the electrode assembly 10 into the firstcasing member 21 and covers the electrode assembly 10 with the secondcasing member 22, and the first and second casing members 21 and 22 arethermally fused on the outer side of the electrode assembly 10 to formthe sealing portion 23.

The first casing member 21 are formed to have such a concave structureso as to accommodate the electrode assembly 10, and the second casingmember 22 is formed to have such a flat structure so as to cover theelectrode assembly 10 accommodated in the first casing member 21. Thefirst and second casing members 21 and 22 may be formed of the polymersheet 121, the nylon sheet 122, and the metal sheet 123 having the samelayer structure.

Referring again to FIG. 3 , the negative electrode plate 11 is formed asa double-sided coated region formed by coating an active material onopposite surfaces of the substrate 31. The negative electrode plate 12includes a double-sided coated region 361 formed by coating an activematerial on opposite surface of the substrate 35 and a single-sidedcoated region 362 formed by coating an active material on one surface ofthe substrate 35.

In the negative electrode plate 12, the single-sided coated region 362may be disposed at at least one of a winding center of the electrodeassembly 10 and an outermost wound position. In the first exemplaryembodiment, the single-sided coated region 362 of the negative electrodeplate 12 is disposed at the winding center and the outermost woundposition in the electrode assembly 10.

In general, resistance of the single-sided coated region is relativelylow compared to the double-sided coated region in the negative electrodeplate, and thus a current amount of the single-sided coated region ishigher than that of the double-sided coated region. As a result, adifference in the current amounts between the double-sided coated regionand the single-sided coated region is large.

In the first exemplary embodiment, the resistance of the single-sidedcoated region 362 is set to be higher than that of the double-sidedcoated region 361 in the negative electrode plate 12. Therefore, thecurrent amount difference between the single-sided coated region 362 andthe double-sided coated region 361 of the negative electrode plate 12may be minimized. In other words, the negative electrode plate 12 isuniformly deteriorated in the single-sided coated region 362 and thedouble-sided coated region 361 of the negative electrode plate 12, sothe cycle-life of the rechargeable battery may be improved.

Hereinafter, specific exemplary embodiments for improving the cycle-lifeof the rechargeable battery by minimizing the current amount differencebetween the single-sided coated region 362 and the double-sided coatedregion 361 of the negative electrode plate 12 will be described.

FIG. 4 illustrates a partial cross-sectional view of a negativeelectrode plate, which is applied to the electrode assembly of FIG. 3 .Referring to FIG. 4 , in the negative electrode plate 12 of the firstexemplary embodiment, the double-sided coated region 361 is formed onthe opposite surfaces of the substrate 35 to have a first thickness t1,and the single-sided coated region 362 is formed on the single surfaceof the substrate 35 to have a second thickness t2 that is larger thanthe first thickness t1.

The single-sided coated region 362 forms a higher loading level of theactive material than the double-side coated region 361. As the loadinglevel increases, solid content and viscosity of an active materialslurry increase, and thus a contact area between the single-sided coatedregion 362 and the substrate 35 becomes smaller, to increase theresistance.

Since the contact area between the active material of the double-sidedcoated region 361 and the substrate 35 is larger than the contact areabetween the active material of the single-sided coated region 362 andthe substrate 35 at a same current, a voltage applied to thedouble-sided coated region 361 is relatively low as compared with avoltage applied to the double-sided coated region 362. Therefore, thesingle-sided coated region 362 has higher resistance than thedouble-sided coated region 361.

FIG. 5 illustrates a partial cross-sectional view of a negativeelectrode plate, which is applied to an electrode assembly of arechargeable battery according to a second exemplary embodiment of thepresent invention. Referring to FIG. 5 , the negative electrode plate 52of the second exemplary embodiment, a double-sided coated region 521 isformed by coating an active material on the opposite surfaces of thesubstrate 35, and a single-sided coated region 522 further includes abinder layer 523 formed by pattern-coating a binder on the singlesurface of the substrate 35. That is, the single-sided coated region 522is formed by coating an active material on the binder layer 523.

For example, a CMC series such as sodium carboxymethyl cellulose(composition range: 1.59 g/ml (cellulose 1.5 g/ml), degree ofsubstitution (DS): 0.6-0.8), styrene-butadiene rubber (e.g.,acrylonitrile-butadiene-styrene rubber having methyl methacrylateincorporated therein), or one of these coated with itaconic acid,acrylamide, acrylonitrile, acrylic acid, methacrylic acid,2-hydroxyethyl acrylate, or a combination thereof, may be used as thebinder.

The binder layer 523 increases the resistance between the single-sidedcoated region 522 and the substrate 35 while increasing a binding forcebetween the single-sided coated region 522 and the substrate 35.Therefore, the single-sided coated region 522 has higher resistance thanthe double-sided coated region 521.

FIG. 6 illustrates a partial cross-sectional view of a negativeelectrode plate, which is applied to an electrode assembly of arechargeable battery according to a third exemplary embodiment of thepresent invention. Referring to FIG. 6 , in the negative electrode plate62 of the third exemplary embodiment, a double-sided coated region 621further includes a carbon-coating layer 623 provided on the oppositesurfaces of the substrate 35. That is, the double-sided coated region621 is formed by coating an active material on the carbon coating layers623. A single-sided coated region 622 is formed by pattern-coating theactive material on the single surface of the substrate 35 to prevent thesingle-sided coated region 622 from including the carbon-coating layer.

The carbon-coating layer 623 reduces the resistance of the double-sidedcoated region 621 and the substrate 35. In contrast, the single-sidedcoated region 622 that does not include the carbon-coating layer and thesubstrate 35 have high resistance. Therefore, the single-sided coatedregion 622 has higher resistance than the double-sided coated region621.

FIG. 7 illustrates a partial cross-sectional view of a negativeelectrode plate, which is applied to an electrode assembly of arechargeable battery according to a fourth exemplary embodiment of thepresent invention. Referring to FIG. 7 , in the negative electrode plate72 of the fourth embodiment, a double-sided coated region 721 is formedof an oriented layer by coating an active material on the oppositesurfaces of the substrate 35, and a single-sided coated region 722 isformed of an non-oriented layer by coating an active material on thesingle surface of the substrate 35.

The oriented double-coated region 721 and the substrate 35 have lowresistance. In contrast, the non-oriented single-sided coated region 722and the substrate 35 have high resistance. Therefore, the single-sidedcoated region 722 has higher resistance than the double-sided coatedregion 721.

FIG. 8 illustrates a partial cross-sectional view of a negativeelectrode plate, which is applied to an electrode assembly of arechargeable battery according to a fifth exemplary embodiment of thepresent invention. Referring to FIG. 8 , in the negative electrode plate82 of the fifth embodiment, a double-sided coated region 821 is formedof a high oriented layer by coating an active material on the oppositesurfaces of the substrate 35, and a single-sided coated region 822 isformed of a low oriented layer that is oriented less than the highoriented layer by coating an active material on the single surface ofthe substrate 35.

The high oriented double-coated region 821 and the substrate 35 have lowresistance. In contrast, the low oriented single-sided coated region 822and the substrate 35 have high resistance. Therefore, the single-sidedcoated region 822 has higher resistance than the double-sided coatedregion 821.

In the fourth and fifth exemplary embodiment disclosed in FIG. 7 andFIG. 8 , the resistances of the single-sided coated regions 722 and 822and the double-sided coated regions 721 and 821 are different asorientation degrees of the double-sided coated regions 721 and 821 andthe single-sided coated regions 722 and 822 are different in thenegative electrode plates 72 and 82.

FIG. 9 illustrates a graph comparing thicknesses, capacities, andcycle-lives of single-sided coated regions of rechargeable batteriesaccording to a conventional art (single-sided coated region anddouble-sided coated region having a same thickness, single-sided coatedregion including carbon-coating layer) and the first and third exemplaryembodiments of the present invention (thickness of single-sided coatedregion being larger than that of double-sided coated region,single-sided coated region including no carbon-coating layer).

Referring to FIG. 9 , the single-sided coated region and thedouble-sided coated region are formed to have a same thickness (notillustrated) in the negative electrode plate of each rechargeablebattery L11 and L12 according to the conventional art, while thethickness t2 of the single-sided coated region 362 is larger than thethickness t1 of the double-sided coated region 361 in the negativeelectrode plate 12 in each rechargeable battery L21 and L22 according tothe first exemplary embodiment (FIG. 4 ).

Therefore, in the first exemplary embodiment, the resistance of thesingle-sided coated region 362 is higher than the resistance of thedouble-sided coated region 361, and thus the current amount differencebetween the single-sided coated region 362 and the double-sided coatedregion 361 is minimized.

This may cause uniform deterioration of the negative electrode plate 12,thereby improving the cycle-life of the rechargeable battery. That is,the rechargeable batteries L21 and L22 according to the first exemplaryembodiment (FIG. 4 ) have longer cycle-lives under conditions of thesame capacity and the same thickness, compared to the rechargeablebatteries L11 and L12 according to the conventional art.

In addition, each rechargeable battery L13 and L14 according to theconventional art includes a carbon-coating layer (not illustrated) inthe single-sided coated region of the negative electrode plate, whileeach rechargeable battery L23 and L24 according to the third exemplaryembodiment (FIG. 6 ) includes no carbon-coating layer in thesingle-sided coated region 622 of the negative electrode plate 62.

Therefore, in the third exemplary embodiment, the resistance of thesingle-sided coated region 622 is higher than the resistance of thedouble-sided coated region 621, and thus the current amount differencebetween the single-sided coated region 622 and the double-sided coatedregion 621 is minimized.

This may cause uniform deterioration of the negative electrode plate 62,thereby improving the cycle-life of the rechargeable battery. That is,the rechargeable batteries L23 and L24 according to the third exemplaryembodiment (FIG. 6 ) have longer cycle-life under conditions of the samecapacity and the same thickness, compared to the rechargeable batteriesL13 and L14 according to the conventional art.

FIG. 10 illustrating a graph comparing capacities and cycle-lives ofrechargeable batteries according to a conventional art (no binder layerbeing applied to single-sided coated region) and the second exemplaryembodiment of the present invention (binder layer being applied tosingle-sided coated region).

Referring to FIG. 10 , no binder is applied to the single-sided coatedregion of the negative electrode plate in a rechargeable battery L25according to the conventional art, while the binder layer 523 is appliedto the single-sided coated region 522 of the negative electrode plate 52in the rechargeable battery L15 according to the second exemplaryembodiment.

Therefore, in the second exemplary embodiment, the resistance of thesingle-sided coated region 522 is higher than the resistance of thedouble-sided coated region 521, and thus the current amount differencebetween the single-sided coated region 522 and the double-sided coatedregion 521 is minimized.

This may cause uniform deterioration of the negative electrode plate 52,thereby improving the cycle-life of the rechargeable battery. That is,the rechargeable battery L15 according to the second exemplaryembodiment (FIG. 5 ) has high capacity, that is, a high current amount,under a condition of the same cycle-life, compared to the rechargeablebattery L25 according to the conventional art.

FIG. 11 illustrates a cross-sectional view of an electrode assembly,which is applied to the rechargeable battery of FIG. 1 according to amodified exemplary embodiment. Referring to FIG. 11 , in the exemplaryelectrode assembly 210 of the modified exemplary embodiment, a substrate231 of a positive electrode plate 211 may be further spiral-wound insidethe single-sided coated region 362 of the negative electrode plate 12 atthe winding center. Further, the substrate 231 of the positive electrodeplate 211 is further spirally wound on the outermost wound position ofthe single-sided coated region 362 of the negative electrode plate 12.

Since the substrate 231 of the positive electrode plate 211 is furtherextended from at least one of the winding center and the outermost woundposition of the electrode assembly 210, when a conductive member (notillustrated) extends through the rechargeable battery, it is possible toincrease the number of short-circuit points.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

<Description of Symbols> 10, 210: electrode assembly 11, 211: firstelectrode plate (positive electrode plate) 12: second electrode plate(negative 13: separator electrode plate) 14, 15: electrode tab 20: pouch21: first casing member 22: second casing member 23: sealing portion 31,35, 231: substrate 32, 36: coated region 33, 37: uncoated region 52, 62,72, 82: negative electrode plate 121: polymer sheet 122: nylon sheet123: metal sheet 361, 521, 621, 721, 821: double-sided coated region362, 522, 622, 722, 822: single-sided coated region 523: binder layer623: carbon-coating layer L11, L12, L13, L14, L25: rechargeable batteryof conventional art L21, L22, L23, L24: rechargeable battery of firstexemplary embodiment L15: rechargeable battery of second exemplaryembodiment t1, t2: first, second thickness

1. An electrode assembly, comprising: an electrode plate at oppositesides of a separator, the electrode plate including: a double-sidedcoated region including an active material on opposite sides of asubstrate forming a current collector; and a single-sided coated regionincluding an active material on a single surface of the substrate,wherein the single-sided coated region has a resistance that is higherthan a resistance of the double-sided coated region.
 2. The electrodeassembly as claimed in claim 1, wherein the single-sided coated regionis at at least one of a winding center of the electrode assembly and anoutermost wound position thereof.
 3. The electrode assembly as claimedin claim 1, wherein the electrode plate includes: a negative electrodeplate on a first surface of the separator to form a negative electrode;and a positive electrode plate on a second surface of the separator toform a positive electrode, and the single-sided coated region is in thenegative electrode plate.
 4. The electrode assembly as claimed in claim3, wherein a substrate of the positive electrode plate is spiral-woundinside the single-sided coated region of the negative electrode plate atthe winding center.
 5. The electrode assembly as claimed in claim 3,wherein a substrate of the positive electrode plate is spirally wound onan outermost wound position of the single-sided coated region of thenegative electrode plate.
 6. The electrode assembly as claimed in claim1, wherein the active material on both sides in the double-sided coatedregion has a first thickness, and the active material on thesingle-sided coated region has a second thickness that is thicker thanthe first thickness.
 7. The electrode assembly as claimed in claim 1,wherein the single-sided coated region includes a binder layer on thesubstrate and the active material on the binder layer.
 8. The electrodeassembly as claimed in claim 1, wherein the double-sided coated regionincludes a carbon-coating layer on opposite surfaces of the substrateand the active material on the carbon-coating layer.
 9. The electrodeassembly as claimed in claim 1, wherein the active material on bothsides in the double-sided coated region are oriented layers, and theactive material in the single-sided coated region is a non-orientedlayer.
 10. The electrode assembly as claimed in claim 1, wherein theactive material on both sides in the double-sided coated region are highoriented layers, and the active material in the single-sided coatedregion is a low oriented layer that is oriented less than the highoriented layers.